Energy calculators

How energy costs are worked out

Most running-cost tools follow the same chain: convert watts to kilowatts, multiply by runtime to get kilowatt-hours, then multiply by your electricity price. A 1,000-watt appliance uses 1kWh per hour at full rated power.

Enter the unit price you actually pay per kWh; rates shown in examples are adjustable illustrations, not a tariff supplied by your energy company. These calculations apply one flat unit rate and do not include standing charges, time-of-use pricing or tariff changes. A nameplate power rating is not necessarily the appliance's average draw: thermostats, variable settings and duty cycles can reduce actual energy use. For washers, dishwashers and dryers, use the model/programme's stated kWh per cycle when available; otherwise treat a power-times-duration estimate as approximate.

Choose the electric-heater cost calculator for heater wattage, days per week and weekly/yearly results; use the appliance running-cost calculator for a general device; or start with the kWh cost calculator when you already know the energy used.